1. Field of Invention
The present invention relates to a liquid crystal device and an electronic apparatus. More specifically, the invention relates to a technology for obtaining a wider viewing angle for the liquid crystal display device using homeotropic liquid crystal.
2. Description of Related Art
A liquid crystal device having a reflective mode and a transmissive mode is known as a transreflective liquid crystal device. Such a transreflective liquid crystal device has a liquid crystal layer interposed between an upper substrate and a lower substrate. A reflective film having a window for transmitting light through the film, composed of a metal plate, e.g., an aluminum plate, is disposed on the inner surface of the lower substrate. The reflective film functions as a transreflective plate. In such a case, in the reflective mode, the light entering from the upper substrate is transmitted through the liquid crystal layer and, then, is reflected at the reflective film on the inner surface of the lower substrate. The light passes through the liquid crystal layer again and is emitted out from the upper substrate to be used for displaying an image. In the transmissive mode, the light from the backlight enters from the lower substrate and passes through the window on the reflective film and then through the liquid crystal layer. Subsequently, the light is emitted to the outside from the upper substrate to be used for displaying an image.
Consequently, the area on the reflective film where the window is formed functions as a transmissive display area and the other areas functions as a reflective display area.
Known transreflective liquid crystal devices have a problem in which the viewing angle is small in transmissive display. This is because only one polarization plate disposed on the viewer's side can be used for reflective display because a transreflective plate is disposed on the inner surface of the liquid crystal cell to prevent parallax, causing the flexibility in the optical design of the device to become small. To solve this problem, Jisaki et al. proposed, in “Development of transreflective LCD for high contrast and wide viewing angle by using homeotropic alignment,” M. Jisaki et al., Asia Display/IDW′01, p. 133-136 (2001), a new liquid crystal display device using homeotropic liquid crystal. This new liquid crystal display device has three characteristics:
1) operating in a vertical alignment mode wherein liquid crystal molecules having negative dielectric anisotropy are aligned vertically relative to a substrate and, then, are tilted by applying a voltage;
2) having a multi-gap structure wherein the thickness of the liquid crystal layer (cell gap) in the transmissive display area and in the reflective display area differ (for example, refer to Japanese Unexamined Patent Application Publication No. 11-242226);
3) having a multi-domain structure wherein the transmissive display area is shaped as a regular octagon with a projection formed in the center of the regular octagon on the opposing substrate so that the liquid crystal molecules tilt in eight different directions within the transmissive display area.
See also, generally, Japanese Unexamined Patent Application Publication No. 2002-350853.